Battery cell and battery module including the same

Abstract

A battery cell according to an embodiment of the present invention includes: a battery case that houses an electrode assembly in a storage unit, and the battery case includes a sealed portion having a structure with a sealed outer periphery; an electrode lead electrically connected to an electrode terminal included in the electrode assembly, and the electrode lead protrudes in an outward direction of the battery case through the sealed portion; and a lead film located at a portion corresponding to the sealed portion at an upper portion and / or a lower portion of the electrode lead, wherein the lead film has a recessed portion recessed in an outer direction of the battery case, the recessed portion opens toward the inside of the battery case, the recessed portion includes a first recessed portion and a second recessed portion, and a width of the second recessed portion is greater than a width of the first recessed portion.

Description

Technical Field

[0001] This application claims priority to Korean Patent Application No. 10-2021-0016111, filed in Korea on February 4, 2021.

[0002] The present disclosure relates to a battery cell and a battery module including the battery cell, and more particularly, to a battery cell in which external discharge of gas generated inside the battery cell is improved and a battery module including the battery cell. Background Art

[0003] With the development of technology and the increasing demand for mobile devices, the demand for secondary batteries as an energy source is rapidly increasing. In particular, secondary batteries are attracting attention as an energy source not only for mobile devices such as mobile phones, digital cameras, laptop computers, and wearable devices but also for power devices such as electric bicycles, electric vehicles, and hybrid vehicles.

[0004] Depending on the shape of the battery case, these secondary batteries are classified into cylindrical batteries and prismatic batteries in which the electrode assembly is included in a cylindrical or prismatic metal can, and pouch-type batteries in which the electrode assembly is included in a pouch-type case made of aluminum laminate. Here, the battery assembly included in the battery case is a power element including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode and capable of charging and discharging, and is classified into a jelly-roll type and a stacked type. In the jelly-roll type, a long strip-type positive electrode and negative electrode coated with an active material are wound with a separator interposed between the positive electrode and the negative electrode, and in the stacked type, a plurality of positive electrodes and negative electrodes are sequentially stacked with a separator interposed between the positive electrode and the negative electrode.

[0005] Among them, in particular, pouch-type batteries in which a stacked or stacked / folded type battery assembly is included in a pouch-type battery case made of aluminum laminate are increasingly used due to low manufacturing cost, small weight, and easy modification.

[0006] Figure 1 is a top view showing a conventional battery cell. Figure 2 is along Figure 1 taken along the axis a-a' of the cross-sectional view. Referring to Figure 1 and Figure 2 , the conventional battery cell 10 includes a battery case 20 having a receiving portion 21 in which a battery assembly 11 is installed and a sealing portion 25 formed by sealing the outer periphery of the battery case 20. Here, the battery cell 10 includes electrode leads 30 protruding to the outside of the battery case 20 through the sealing portion 25, and a lead film 40 is located between the upper and lower portions of the electrode leads 30 and the sealing portion 25.

[0007] However, with the increase in the energy density of battery cells in recent years, there is a problem that the amount of gas generated inside the battery cell also increases. In the case of a conventional battery cell 10, there is no component capable of discharging the gas generated inside the battery cell, so due to the generation of gas, gas exhaust may occur in the battery cell. In addition, moisture can penetrate into the battery cell damaged by gas exhaust, which can cause side reactions, and there are problems of deterioration of battery performance and generation of additional gas. Therefore, there is an increasing need to develop a battery cell in which the external discharge of gas generated inside the battery cell is improved. Summary of the Invention

[0008] Technical Problem

[0009] The present disclosure relates to providing a battery cell in which the external discharge of gas generated inside the battery cell is improved and a battery module including the battery cell.

[0010] The object to be solved by the present disclosure is not limited to the above-mentioned object, and those skilled in the art can clearly understand the object not mentioned here through the present specification and the drawings.

[0011] Technical Solution

[0012] In one aspect of the present disclosure, there is provided a battery cell including: a battery case having a receiving portion for mounting an electrode assembly therein and a sealing portion formed by sealing the outer periphery of the battery case; an electrode lead wire electrically connected to an electrode terminal included in the electrode assembly and protruding out of the battery case via the sealing portion; and a lead film located at a portion corresponding to the sealing portion in at least one of an upper portion and a lower portion of the electrode lead wire, wherein the lead film has a recessed portion recessed in an outer direction of the battery case, the recessed portion opening toward the inside of the battery case, the recessed portion includes a first recessed portion and a second recessed portion, and the width of the second recessed portion is greater than the width of the first recessed portion.

[0013] The second recessed portion may be positioned farther from the received electrode assembly than the first recessed portion.

[0014] A portion of the first recessed portion may be located at a position corresponding to the sealing portion.

[0015] A portion of the second recessed portion may be located at a position not corresponding to the sealing portion.

[0016] The width of the lead film may be greater than the width of the sealing portion and less than the length of the electrode lead wire.

[0017] The second recessed portion may be located between the end of the sealing portion and the end of the lead film.

[0018] The first recessed portion may extend along the protruding direction of the electrode lead, and the second recessed portion may extend along the longitudinal direction of the sealing portion.

[0019] The second recessed portion may have a circular shape, a triangular shape, a rectangular shape, or an uneven shape.

[0020] The inner surface of the recessed portion may be closed based on the protruding direction of the electrode lead.

[0021] The lead film may further include an inner layer configured to cover at least one surface of the inner surface of the recessed portion of the lead film.

[0022] The material of the inner layer may have a higher melting point than the material of the lead film and may not react with the electrolyte solution.

[0023] The lead film may comprise a polyolefin-based material.

[0024] The inner layer may comprise at least one of a polyolefin-based material, a fluorine-based material, and a porous ceramic-based material.

[0025] The recessed portion may be located above the electrode lead.

[0026] The lead film may have a length greater than the width of the electrode lead.

[0027] The recessed portion may be located between the end of the electrode lead and the end of the lead film.

[0028] The lead film may include a first lead film and a second lead film. The first lead film may be located at the upper portion of the electrode lead, and the second lead film may be located at the lower portion of the electrode lead.

[0029] The electrode lead may be located between the first lead film and the second lead film, and the first lead film and the second lead film may be connected to each other.

[0030] The recessed portion may be located in at least one of the first lead film and the second lead film.

[0031] The end of the recessed portion at the outermost side of the battery case may be positioned more outwardly than the outer surface of the battery case.

[0032] The end of the recessed portion facing the inner opening of the battery case may be positioned more inwardly than the inner surface of the battery case.

[0033] Based on the protruding direction of the electrode lead, the width of the lead film around the front surface of the recessed portion may be 2 mm or more.

[0034] The thickness of the lead film around the upper surface of the recessed portion may be 100 μm to 300 μm.

[0035] The lead film may have a gas permeability of 20 Barrer to 60 Barrer at 60°C.

[0036] The lead film may have a moisture permeation amount of 0.02 g to 0.2 g at 25°C, 50% RH, and within 10 years.

[0037] In another aspect of the present disclosure, a battery module is also provided, which includes the above-described battery cell.

[0038] Advantageous Effects

[0039] According to an embodiment, the present disclosure provides a battery cell and a battery module including the battery cell, thereby improving the external emission of gas generated inside the battery cell. The battery cell includes an electrode lead, and a lead film having a recessed portion recessed in the outer direction of the battery case and facing the inner opening of the battery case is formed on the electrode lead.

[0040] According to an embodiment, in the present disclosure, since the recessed portion includes a first recessed portion and a second recessed portion, and the width of the second recessed portion is greater than the width of the first recessed portion, the external emission of gas generated inside the battery cell can be improved and the durability of the lead film can be improved.

[0041] The effects of the present disclosure are not limited to the above effects, and those skilled in the art will clearly understand the effects not mentioned here through this specification and the drawings. Description of the Drawings

[0042] Figure 1 is a top view showing a conventional battery cell.

[0043] Figure 2 is along Figure 1 the axis a-a' of the cross-sectional view.

[0044] Figure 3 is a top view showing the battery cell according to this embodiment.

[0045] Figure 4 is showing Figure 3Stereogram of the electrode lead included in the battery cell.

[0046] Figure 5 is a sectional view taken along Figure 4 axis c-c' of

[0047] Figure 6 is a sectional view taken along Figure 4 axis d-d' of

[0048] Figure 7 is a sectional view taken along Figure 4 axis e-e' of

[0049] Figure 8 shows an enlarged view of the electrode lead in the battery cell of Figure 3

[0050] Figure 9 shows an enlarged view of the electrode lead showing the position of the sealing portion in (a) according to Figure 8

[0051] Figure 10 shows an enlarged view of the electrode lead in the battery cell of Figure 3 according to another embodiment of the present disclosure.

[0052] Figure 11 shows an enlarged view of the electrode lead in the battery cell of Figure 3 according to another embodiment of the present disclosure.

[0053] Figure 12 shows an enlarged view of the electrode lead in the battery cell of Figure 3 according to another embodiment of the present disclosure.

[0054] Figure 13 is a sectional view taken along Figure 3 axis b-b' of

[0055] Figure 14 shows Figure 13 the flow of gas generated in the battery cell and discharged to the outside in Detailed Description of Embodiments

[0056] Hereinafter, various embodiments of the present disclosure will be described in detail with reference to the accompanying drawings so that they can be easily implemented by those skilled in the art. The present disclosure can be implemented in various different forms and is not limited to the embodiments described herein.

[0057] To clearly illustrate the present disclosure, parts irrelevant to the description are omitted, and the same reference numerals are assigned to the same or similar components throughout the specification. ​​

[0058] In addition, since the sizes and thicknesses of each component shown in the figures are arbitrarily expressed for convenience of description, the present disclosure is not necessarily limited to the drawings. The thicknesses are enlarged in order to clearly express various layers and regions in the figures. In addition, in the drawings, the thicknesses of some layers and regions are exaggerated for convenience of explanation.

[0059] In addition, throughout the specification, when a part "includes" a certain component, this means that other components may also be included, rather than excluding other components, unless otherwise specified.

[0060] In addition, throughout the specification, when referring to a "top view", this means observing the target part from above, and when referring to a "cross-sectional view", this means observing a longitudinal cross-section of the target part from the side.

[0061] Hereinafter, a pouch-type battery cell 100 according to an embodiment of the present disclosure will be described. However, here, the description will be based on one of the two side surfaces of the pouch-type battery cell 100, but it is not necessarily limited thereto, and the same or similar content can be described in the case of the other side surface.

[0062] Figure 3 is a top view showing the battery cell according to this embodiment.

[0063] Referring to Figure 3 , the battery cell 100 according to this embodiment includes a battery case 200, electrode leads 300, and a lead film 400.

[0064] The battery case 200 includes a receiving portion 210 in which the electrode assembly 110 is installed and a sealing portion 250 formed by sealing the outer periphery of the battery case 200. The sealing portion 250 can be sealed by heat, laser, etc. The battery case 200 can be a laminated sheet including a resin layer and a metal layer. More specifically, the battery case 200 can be made of a laminated sheet and can include an outer resin layer forming the outermost layer, a barrier metal layer for preventing material penetration, and an inner resin layer for sealing.

[0065] In addition, the electrode assembly 110 can have a jelly-roll type (wound type), a stacked type (laminated type), or a composite type (stacked / folded type) structure. More specifically, the electrode assembly 110 can include a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode.

[0066] Hereinafter, the electrode leads 300 and the lead film 400 will be mainly described.

[0067] Figure 4 is a perspective view showing the electrode leads included in the Figure 3 battery cell.

[0068] Referring toFigure 3 and Figure 4 The electrode lead 300 is electrically connected to an electrode joint (not shown) included in the electrode assembly 110 and protrudes outside the battery case 200 via the sealing portion 250. In addition, the lead film 400 is located at a portion corresponding to the sealing portion 250 in at least one of the upper portion and the lower portion of the electrode lead 300. Therefore, the lead film 400 can improve the sealing performance between the sealing portion 250 and the electrode lead 300 while preventing a short circuit from occurring in the electrode lead 300 during sealing.

[0069] Figure 5 is a cross-sectional view taken along the Figure 4 axis c-c' Figure 6 is a cross-sectional view taken along the Figure 4 axis d-d' Figure 7 is a cross-sectional view taken along the Figure 4 axis e-e'

[0070] Referring to Figure 5 , the lead film 400 has a recessed portion 450 that is recessed in the outer direction of the battery case 200, and the recessed portion 450 opens toward the inside of the battery case 200. In addition, the inner surface of the recessed portion 450 can be closed based on the protruding direction of the electrode lead 300.

[0071] Therefore, in the lead film 400, if the gas generated inside the battery case 200 exceeds a predetermined pressure, the gas can be discharged into the recessed portion 450, and the gas introduced into the recessed portion 450 can be discharged to the outside of the battery according to the pressure difference between the inside and the outside. In addition, since the recessed portion 450 of the lead film 400 opens toward the inside and at the same time the inner surface of the recessed portion recessed in the outer direction of the lead film 400 is closed, there is an advantage that the airtightness and durability of the bag can be ensured. In addition, in the lead film 400, the gas permeation area can be maximized through the recessed portion 450, so that a large amount of gas can be discharged.

[0072] Referring to Figure 6 and Figure 7 , the recessed portion 450 includes a first recessed portion 451 and a second recessed portion 455, and the width of the second recessed portion 455 is greater than the width of the first recessed portion 451.

[0073] In the present specification, the width of the second recessed portion 455 refers to the maximum value of the distance between one end and the other end of the second recessed portion 455 in a direction orthogonal to the protruding direction of the electrode lead 300, and the width of the first recessed portion 451 refers to the maximum value of the distance between one end and the other end of the first recessed portion 451 in a direction orthogonal to the protruding direction of the electrode lead 300.

[0074] If the curvature increases as the lead film 400 expands outward under pressure due to the inflow of gas inside the battery case 200 into the recessed portion 450, the stress applied to the interface between the lead film 400 and the electrode lead 300 also increases.

[0075] If the recessed portion 450 has exactly the same width, the durability of the lead film 400 may become weak due to the stress applied to the interface between the lead film 400 and the electrode lead 300 as the curvature of the expanding lead film 400 increases.

[0076] In addition, if the recessed portion 450 includes a first recessed portion 451 and a second recessed portion 455 having different widths, since the curvature of the lead film 400 expanding in the first recessed portion 451 with a relatively small width is smaller than the curvature of the lead film 400 expanding in the second recessed portion 455 with a relatively large width, the stress applied to the interface between the lead film 400 and the electrode lead 300 is small, so the durability can be improved and gas emission can be improved.

[0077] In addition, referring to Figures 5 to 7 , the lead film 400 may further include an inner layer 410 covering at least one inner surface of the recessed portion 450.

[0078] For example, referring to Figure 5 (a) to Figure 7 (a), the inner layer 410 in the recessed portion 450 may cover the entire surface of the lead film 400. That is, the inner layer 410 may be formed on the entire inner surface of the recessed portion 450 except for the open surface.

[0079] Therefore, even if the lead film 400 is sealed together with the sealing portion 250 in a state where it is located in at least one of the upper portion and the lower portion of the electrode lead 300, the recessed portion 450 can be kept in an unsealed state through the inner layer 410.

[0080] As another example, referring to Figure 5 (b) to Figure 7 (b), the inner layer 410 may cover the upper surface or the lower surface among the inner surfaces of the recessed portion 450. That is, the recessed portion 450 may have an inner layer 410 formed on at least one of the upper surface and the lower surface facing each other.

[0081] Therefore, although the lead film 400 minimizes the inner layer 410 formed in the recessed portion 450, the recessed portion 450 can be kept in an unsealed state through the inner layer 410. In addition, the manufacturing process can be simplified and the cost can be reduced.

[0082] More specifically, the inner layer 410 can be made of a material having a higher melting point than the material constituting the lead film 400. Additionally, the inner layer 410 can be made of a material that does not react with the electrolyte solution contained in the battery case 200. Thus, since the inner layer 410 is made of the above materials, the inner layer 410 does not react with the electrolyte solution individually and does not cause heat fusion, thermal deformation, etc. during the high-temperature sealing process, enabling the recessed portion 450 to remain empty. Additionally, the gas generated in the battery case 200 can be easily discharged to the outside.

[0083] In one embodiment of the present disclosure, the thickness of the inner layer 410 can be 100 μm or less.

[0084] In one embodiment of the present disclosure, the gas permeability of the inner layer 410 can be 40 bar or greater. For example, the carbon dioxide permeability of the inner layer 410 can meet the above range.

[0085] For example, the inner layer 410 can include at least one of polyolefin materials, fluorine materials, and porous ceramic materials. For example, the inner layer 410 can include at least one of polyolefin materials, fluorine materials, and porous ceramic materials that satisfy the above gas permeability values. The polyolefin materials can include at least one material selected from the group consisting of polypropylene, polyethylene, and polyvinylidene fluoride (PVDF). The fluorine materials can include at least one material selected from the group consisting of polytetrafluoroethylene and polyvinylidene fluoride. Additionally, the inner layer 410 can include a getter material such that the gas permeability can be increased while minimizing the water permeability. As an example, the getter material can be calcium oxide (CaO), barium oxide (BaO), lithium chloride (LiCl), silicon dioxide (SiO2), etc., and any material that reacts with water (H2O) can be used, without being limited thereto.

[0086] The inner layer 410 can have an adhesive material between the lead film 400 and the inner layer 410, or can be extruded together with the lead film 400 and adhered to the lead film 400. The adhesive material can include an acryl-based material. In particular, when the inner layer 410 is extruded together with the lead film 400, the gas permeability of the inner layer 410 can be 40 bar or greater.

[0087] Referring to Figures 4 to 7 , the lead film 400 can include a first lead film and a second lead film. The first lead film can be located at the upper portion of the electrode lead 300, and the second lead film can be located at the lower portion of the electrode lead 300. At this time, the electrode lead 300 can be sealed together with the sealing portion 250 in a state of being located between the first lead film and the second lead film, such that the first lead film and the second lead film can be connected to each other.

[0088] Therefore, the lead film 400 can prevent the side surface of the electrode lead 300 from being exposed to the outside while improving the sealing performance between the sealing portion 250 and the electrode lead 300.

[0089] For example, in the lead film 400, the recessed portion 450 may be located in at least one of the first lead film and the second lead film. More specifically, in the lead film 400, the recessed portion 450 may be formed in the first lead film or the second lead film based on the electrode lead 300, or the recessed portion 450 may be formed in both the first lead film and the second lead film based on the electrode lead 300. However, the number of the recessed portions 450 is not limited to the above, and the lead film 400 may be formed in an appropriate number.

[0090] Therefore, by adjusting the number of the recessed portions 450 formed in the lead film 400, the durability and airtightness of the lead film 400 can be controlled. In addition, by minimizing the number of the recessed portions 450 when necessary, the manufacturing process can be simplified and the cost can be reduced.

[0091] Figure 8 is a magnified view of the electrode lead in the Figure 3 battery cell shown. Figure 9 is a magnified view of the electrode lead showing the position of the sealing portion in (a) according to Figure 8 the same.

[0092] Referring to Figure 8 , the second recessed portion 455 may be positioned farther from the accommodated electrode assembly 110 than the first recessed portion 451.

[0093] At this time, the second recessed portion 455 may function to discharge the gas generated inside the battery case 200 to the outside of the battery case 200. Therefore, since the width of the second recessed portion 455 is greater than the width of the first recessed portion 451, the area through which the gas is discharged to the outside is further increased, and thus it is easier to increase the gas discharge.

[0094] In addition, the first recessed portion 451 having a relatively small width may be used as a passage through which the gas generated inside the battery case 200 flows into the recessed portion 450, and the durability of the lead film 400 may be increased.

[0095] Referring to Figure 8 , a portion of the first recessed portion 451 may be located at a position corresponding to the sealing portion 250. For example, the second recessed portion 455 may be positioned farther from the accommodated electrode assembly 110 than the first recessed portion 451, and in addition, a portion of the first recessed portion 451 may be located at a position corresponding to the sealing portion 250.

[0096] Referring to Figure 8, a portion of the second recessed portion 455 may be located at a position not corresponding to the sealing portion 250. In this case, as the area where the second recessed portion 455 does not correspond to the sealing portion 250 increases, the area where the gas inside the battery case 200 is discharged to the outside of the battery case 200 may increase. For example, although the second recessed portion 455 is positioned farther from the accommodated electrode assembly 110 than the first recessed portion 451, a portion of the second recessed portion 455 may be located at a position not corresponding to the sealing portion 250.

[0097] In an embodiment of the present disclosure, the width of the lead film 400 may be greater than the width of the sealing portion 250 and may be less than the length of the electrode lead 300. In this specification, the length of the lead film 400 means the maximum value of the distance between one end and the other end of the lead film 400 in the protruding direction of the electrode lead 300. The width of the sealing portion 250 means the maximum value of the distance between one end and the other end of the sealing portion 250 in the protruding direction of the electrode lead 300. The length of the electrode lead 300 means the maximum value of the distance between one end and the other end of the electrode lead 300 in the protruding direction of the electrode lead 300. At this time, the second recessed portion 455 may be located between the end of the sealing portion 250 and the end of the lead film 400. For example, the second recessed portion 455 may be completely located at a position not corresponding to the sealing portion 250.

[0098] In the lead film 400, the recessed portion 450 may be formed in various shapes.

[0099] Referring to Figure 8 , the first recessed portion 451 may extend along the protruding direction of the electrode lead 300, and the second recessed portion 455 may extend along the longitudinal direction of the sealing portion 250. In this specification, the longitudinal direction of the sealing portion 250 refers to the direction orthogonal to the protruding direction of the electrode lead 300.

[0100] In the lead film 400, the recessed portion 450 may be formed at various positions with respect to the electrode lead 300.

[0101] For example, as shown in (a) of Figure 8 , in the lead film 400, the recessed portion 450 may be located above the electrode lead 300. More specifically, the recessed portion 450 may be formed at a position corresponding to the middle portion of the electrode lead 300.

[0102] As another example, as shown in Figure 8As shown in (b), the length of the lead film 400 can be greater than the width of the electrode lead 300, and the recessed portion 450 can be located between the end of the electrode lead 300 and the end of the lead film 400. Here, the length of the lead film 400 means the maximum value of the distance between one end and the other end of the lead film 400 in a direction orthogonal to the protruding direction of the electrode lead 300, and the width of the electrode lead 300 means the maximum value of the distance between one end and the other end of the electrode lead 300 in a direction orthogonal to the protruding direction of the electrode lead 300. In other words, in the lead film 400, the recessed portion 450 can be formed at a position avoiding the electrode lead 300. However, the position of the recessed portion 450 is not limited to the above, and the recessed portion 450 can be formed at an appropriate position within the lead film 400.

[0103] Therefore, by adjusting the position of the recessed portion 450 formed in the lead film 400, the durability and airtightness of the lead film 400 can be controlled. Additionally, if necessary, by adjusting the size of the recessed portion 450 according to the position of the recessed portion 450, the manufacturing process can be simplified and the cost can be reduced.

[0104] Refer to Figure 9 , in the lead film 400, the end of the recessed portion 450 opening inward can be formed adjacent to the end of the lead film 400 facing the inside of the battery case 200, and the end of the outermost recessed portion 450 of the battery case 200 recessed outward can be located between the end of the sealing portion 250 and the end of the lead film 400. In this specification, the term "the outermost end of the battery case 200" refers to the end of the recessed portion 450 among the ends of the recessed portion that is located on the outermost side with respect to the protruding direction of the electrode lead 300.

[0105] Furthermore, the end of the recessed portion 450 recessed outward can be spaced apart from the end of the sealing portion 250 by a predetermined distance or can be positioned adjacent thereto.

[0106] For example, if comparing Figure 9 (a) with Figure 9 (b), even if the position of the sealing portion 250 in contact with the lead film 400 changes, it can be found that the region of the recessed portion 450 located outside the battery case 200 is not affected.

[0107] Therefore, in this embodiment, within the error range based on the positions of the lead film 400 and the sealing portion 250 generated during the sealing process, the region where the recessed portion 450 is located outside the battery case 200 can be uniformly maintained, and the region where the gas in the battery case 200 can be introduced into or discharged from the recessed portion 450 can also be uniformly maintained. Therefore, the advantage is that the exhaust effect of the recessed portion 450 can also be maintained.

[0108] Figures 10 to 12 is an enlarged view of the electrode lead in the battery cell showing other embodiments according to the present disclosure Figure 3 of the battery cell.

[0109] Referring to Figures 10 to 12 , the second recessed portion 455 may have a circular, triangular or uneven shape, but is not limited thereto, and may have, for example, a rectangular shape as shown in Figure 8 .

[0110] Therefore, by adjusting the shape of the recessed portion 450 formed in the lead film 400, the durability and airtightness of the lead film 400 can be controlled. Additionally, if necessary, the shape of the recessed portion 450 can be changed to simplify the manufacturing process and reduce costs.

[0111] Figure 13 is a cross-sectional view taken along the Figure 3 axis b-b'. Figure 14 is a diagram showing Figure 13 the flow of gas generated in the battery cell and discharged to the outside in

[0112] Referring to Figure 13 , the end of the recessed portion 450 at the outermost side of the battery case 200 may be positioned more outwardly than the outer surface of the battery case 200. In this specification, the outer surface of the battery case 200 means the end of the sealing portion 250 of the battery case 200 on the outside of the battery. Therefore, it is possible to more easily and sufficiently ensure the region through which the gas can be discharged to the outside of the battery.

[0113] In addition, the end of the recessed portion 450 that opens toward the inside of the battery case 200 may be positioned more inwardly than the inner surface of the battery case 200. In this specification, the inner surface of the battery case 200 means the end of the sealing portion 250 of the battery case 200 on the inside of the battery. Therefore, the gas in the battery can more easily flow into the recessed portion 450.

[0114] In the above case, the lead film 400 can maximize the area of the recessed portion 450, so that the permeation region of the gas generated inside the battery case 200 can be maximized, and thus a large amount of gas can be discharged.

[0115] Reference Figure 13 As shown in Figure 13 , the thickness H of the lead film 400 around the upper surface of the recessed portion 450 can be 100 μm to 300 μm or 100 μm to 200 μm. If the thickness H of the lead film 400 around the upper surface of the recessed portion 450 satisfies the above range, the gas inside the battery case 200 can be more easily discharged to the outside. In this specification, the lead film 400 around the upper surface of the recessed portion 450 refers to the lead film 400 between the recessed portion 450 and the electrode lead 300.

[0116] Reference Figure 13 As shown in Figure 13 , based on the protruding direction of the electrode lead 300, the width W of the lead film 400 around the front surface of the recessed portion 450 can be 2 mm or more or 2 mm to 3 mm. In this specification, the width of the lead film 400 around the front surface of the recessed portion 450 means the maximum value of the distance between the recessed end of the outermost lead film 400 of the battery case 200 and the end of the lead film 400 outside the battery case 200. If the width W of the lead film 400 around the front surface of the recessed portion 450 satisfies the above range, it is possible to more easily prevent the lead film 400 from being torn when the gas generated inside the battery case 200 is discharged to the outside.

[0117] Reference Figure 14 As shown in Figure 14 , the gas generated inside the battery cell 100 can be discharged toward the recessed portion 450 of the lead film 400. Here, since the recessed portion 450 opens toward the inside, the pressure inside the recessed portion 450 can be the same as the pressure inside the battery case 200.

[0118] The pressure inside the recessed portion 450 is higher than the pressure outside the battery cell 100, and the resulting pressure difference can act as a driving force for the gas. Therefore, the gas introduced into the recessed portion 450 can be easily discharged toward the outside. In addition, the amount of gas generated inside the battery cell 100 can also be increased.

[0119] At this time, the gas generated inside the battery case 200 can be discharged along the Z-axis direction via the recessed portion 450 and the lead film 400 around the upper surface of the recessed portion. For example, when the recessed portion 450 is exposed to the outside of the battery case 200, the gas generated inside the battery case 200 can be discharged along the Z-axis direction via the recessed portion 450 and the lead film 400 around the upper surface of the recessed portion. In particular, when the recessed end of the recessed portion 450 at the outermost side of the battery case is positioned more outside than the outer surface of the battery case 200, the gas can be discharged along the Z-axis direction through the lead film 400 between the recessed end of the outermost recessed portion 450 of the battery case 200 and the outer surface of the battery case 200.

[0120] In one embodiment of the present disclosure, at 60 °C, the gas permeability of the lead film 400 may be from 20 bar to 60 bar or from 30 bar to 40 bar. For example, the carbon dioxide permeability of the lead film 400 may satisfy the above range. In addition, based on the thickness of the lead film 400 of 200 μm, at 60 °C, the gas permeability may satisfy the above range. If the gas permeability of the lead film 400 satisfies the above range, the gas generated inside the secondary battery can be discharged more effectively.

[0121] In this specification, the gas permeability can be measured by ASTM F2476-20.

[0122] In one embodiment of the present disclosure, at 25 °C, 50% RH, within 10 years, the water permeation amount of the lead film 400 may be from 0.02 g to 0.2 g, or from 0.02 g to 0.04 g, or 0.06 g, or 0.15 g. If the water permeation amount of the lead film 400 satisfies the above range, the penetration of water from the lead film 400 can be prevented more effectively.

[0123] The water permeation amount of the lead film 400 can be measured by adopting the ASTM F 1249 method. At this time, a device officially certified by MCOON can be used to measure the water permeation amount.

[0124] In one embodiment of the present disclosure, the lead film 400 may have a gas permeability of from 20 bar to 60 bar at 60 °C and a water permeation amount of from 0.02 g to 0.2 g at 25 °C, 50% RH, within 10 years. If the gas permeability and the water permeation amount of the lead film 400 satisfy the above range, the penetration of water from the outside can be prevented more effectively while discharging the gas generated inside the secondary battery.

[0125] In one embodiment of the present disclosure, the lead film 400 may include a polyolefin resin. For example, the lead film 400 may include a polyolefin resin that satisfies the above gas permeability and / or water permeation amount values. The polyolefin resin may include at least one material selected from the group consisting of polypropylene, polyethylene, and polyvinylidene fluoride (PVDF). Although the lead film 400 contains polypropylene, the gas permeability of the lead film 400 at 60 °C may be from 20 bar to 60 bar. In addition, the water permeation amount may be from 0.06 g to 0.15 g. In this case, the gas generated inside the secondary battery can be discharged more effectively, and the penetration of water from the outside can be easily prevented.

[0126] In addition, since the lead film 400 is made of the above materials, the lead film 400 can maintain the airtightness of the battery cell 100 and prevent the leakage of the internal electrolyte solution.

[0127] A battery module according to another embodiment of the present disclosure includes the above-described battery cells. In addition, one or more battery modules according to this embodiment may be encapsulated in a battery pack housing to form a battery pack.

[0128] The above-described battery module and the battery pack including the battery module may be applied to various devices. These devices may be transportation devices such as electric bicycles, electric vehicles, hybrid vehicles, etc., but the present disclosure is not limited thereto, and the present disclosure may be applied to various devices that can use the battery module and the battery pack including the battery module, which is also within the scope of the rights of the present disclosure.

[0129] Although the preferred embodiments of the present disclosure have been described in detail above, the scope of the rights of the present disclosure is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concept of the present disclosure defined in the appended claims also fall within the scope of the rights of the present disclosure.

Claims

1. A battery cell, the battery cell comprising: A battery case, the battery case having a receiving portion for mounting an electrode assembly therein and a sealing portion formed by sealing the outer periphery of the battery case; An electrode lead, the electrode lead being electrically connected to an electrode terminal included in the electrode assembly, and the electrode lead protruding out of the battery case via the sealing portion; And A lead film, the lead film being located at a portion corresponding to the sealing portion in at least one of the upper portion and the lower portion of the electrode lead, Wherein the lead film has a recessed portion recessed in the outer direction of the battery case, The recessed portion opens toward the inside of the battery case, The recessed portion includes a first recessed portion and a second recessed portion, and The width of the second recessed portion is greater than the width of the first recessed portion, Wherein the second recessed portion is positioned further away from the received electrode assembly than the first recessed portion, and Wherein gas generated inside the battery case is discharged to the outside of the battery case via the lead film surrounding the upper surface of the recessed portion.

2. The battery cell according to claim 1, wherein, A part of the first recessed portion is located at a position corresponding to the sealing portion.

3. The battery cell according to claim 1, wherein, A part of the second recessed portion is located at a position not corresponding to the sealing portion.

4. The battery cell according to claim 1, wherein, The width of the lead film is greater than the width of the sealing portion and less than the length of the electrode lead.

5. The battery cell according to claim 4, wherein, The second recessed portion is located between the end of the sealing portion and the end of the lead film.

6. The battery cell according to claim 1, Among them, The first recessed portion extends along the protruding direction of the electrode lead, and The second recessed portion extends along the longitudinal direction of the sealing portion.

7. The battery cell according to claim 1, wherein, The second recessed portion has a circular shape, a triangular shape, a rectangular shape or an uneven shape.

8. The battery cell according to claim 1, wherein, The inner surface of the recessed portion is closed based on the protruding direction of the electrode lead.

9. The battery cell according to claim 1, wherein, The lead film further includes an inner layer, the inner layer being configured to cover at least one inner surface of the recessed portion.

10. The battery cell according to claim 9, wherein, The material of the inner layer has a higher melting point than the material of the lead film, and the material of the inner layer does not react with the electrolyte solution.

11. The battery cell according to claim 1, wherein, The lead film contains a polyolefin resin.

12. The battery cell according to claim 9, wherein, The inner layer contains at least one of a polyolefin material, a fluorine material and a porous ceramic material.

13. The battery cell according to claim 1, wherein, The recessed portion is located above the electrode lead.

14. The battery cell according to claim 1, wherein, The length of the lead film is greater than the width of the electrode lead.

15. The battery cell according to claim 14, wherein, The recessed portion is located between the end of the electrode lead and the end of the lead film.

16. The battery cell according to claim 1, Among them, The lead film includes a first lead film and a second lead film, The first lead film is located at the upper portion of the electrode lead, and The second lead film is located at the lower portion of the electrode lead.

17. The battery cell according to claim 16, wherein, The electrode lead is located between the first lead film and the second lead film, and the first lead film is connected to the second lead film.

18. The battery cell according to claim 16, wherein, The recessed portion is located in at least one of the first lead film and the second lead film.

19. The battery cell according to claim 1, wherein, The end portion of the recessed part that is on the outermost side of the battery case is positioned more outwardly than the outer surface of the battery case.

20. The battery cell according to claim 1, wherein, The end portion of the recessed part that opens toward the inside of the battery case is positioned more inwardly than the inner surface of the battery case.

21. The battery cell according to claim 1, wherein, Based on the protruding direction of the electrode lead, the width of the lead film around the front surface of the recessed part is 2 mm or more.

22. The battery cell according to claim 1, wherein, The thickness of the lead film around the upper surface of the recessed part is 100 μm to 300 μm.

23. The battery cell according to claim 1, wherein, The lead film has a gas permeability of 20 bar to 60 bar at 60°C.

24. The battery cell according to claim 1, wherein, The lead film has a moisture permeation amount of 0.02 g to 0.2 g at 25°C, 50% RH, over 10 years.

25. A battery module, the battery module comprising a battery cell according to any one of claims 1-24.

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